Small wonder when habits potentially govern so much of what we do. Duhigg quotes one study from Duke University that estimated that habits, rather than conscious decision-making, shape up to 45 percent of the choices we make every day. Hence the concentration by many different types of organisations on the smart collection and re-application of data in order to understand consumer behaviour, how products might become part of existing habit cycles, how to improve targeting or make experiences better, and how to capitalise on the brief periods in our lives (like having a baby or buying a house) when our old routines fall apart and our shopping habits are in a state of flux.

But it was this excerpt concerning the key to radically changing your life that I found particularly enlightening:

'In a 1994 Harvard study that examined people who had radically changed their lives...researchers found that some people had remade their habits after a personal tragedy, such as a divorce or a life-threatening illness. Others changed after they saw a friend go through something awful...

Just as frequently, however, there was no tragedy that preceded people’s transformations. Rather, they changed because they were embedded in social groups that made change easier. One woman said her entire life shifted when she signed up for a psychology class and met a wonderful group. “It opened a Pandora’s box,” the woman told researchers. “I could not tolerate the status quo any longer. I had changed in my core.” Another man said that he found new friends among whom he could practice being gregarious. “When I do make the effort to overcome my shyness, I feel that it is not really me acting, that it’s someone else,” he said. But by practicing with his new group, it stopped feeling like acting. He started to believe he wasn’t shy, and then, eventually, he wasn’t anymore. When people join groups where change seems possible, the potential for that change to occur becomes more real. For most people who overhaul their lives, there are no seminal moments or life-altering disasters. There are simply communities— sometimes of just one other person— who make change believable. One woman told researchers her life transformed after a day spent cleaning toilets— and after weeks of discussing with the rest of the cleaning crew whether she should leave her husband.

“Change occurs among other people,” one of the psychologists involved in the study, Todd Heatherton, told me. “It seems real when we can see it in other people’s eyes.”'